Crud from the EGR is common in these cars. As far as pulling the manifold and cleaning it the crud isn't doing your engine any good, but on the other hand yours doesn't look too bad. Its your call, clean it now or wait till it gets worse.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

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